Hema, a 25-year-old woman has normal vision, but is a carrier of colour blindness (X o X). Her husband is colour blind (X o Y).

(a) 50% of their sons will be colour blind. The mother gives either X^o or X, while the father gives Y to all sons, so half the sons are X^oY (colour blind) and half are XY (normal).

(b) Yes. The father passes X^o to every daughter, so a daughter who receives X^o from the mother will be X^oX^o and colour blind, and a daughter who receives X from the mother will be XX^o and a carrier. Therefore half the daughters will be colour blind and half will be carriers.